1. Field of the Disclosure
The present disclosure relates generally to apparatus and methods for formation fluid collection and testing.
2. Description of the Related Art
During both drilling of a wellbore and after drilling, fluid (oil, gas and water) from the formation (“formation fluid”) is often extracted to determine the nature of the hydrocarbons in hydrocarbon-bearing formations using a formation testing tool that contains one or more chambers or tanks for collecting fluid samples. The fluid samples are tested downhole during collection process and at the surface to determine various properties of the extracted formation fluid. During drilling of a well, a drilling fluid is circulated through a drill string and the annulus between the drill string and the wellbore diameter. The pressure of the drilling fluid on the formation is greater than the pressure of the formation in which the well is drilled. The drilling fluid invades into the formation surrounding the wellbore to varying depths, referred to as the invaded zone, which contaminates the original or connate fluid present in the invaded zone. To collect samples of the original fluid present in the formation, either during drilling or post drilling, a formation testing tool is conveyed into the wellbore. A probe having a fluid line is sealingly pressed against the wellbore wall. A pump typically extracts the fluid from the formation into the probe. The initially extracted fluid is discarded into the wellbore while testing it for contamination. When the extracted fluid is sufficiently clean, fluid samples are collected in one or more chambers (tanks) for analysis. Single and multiple probes have been utilized for extracting formation fluid.
Each sample chamber is typically placed in a tank carrier in the body of the formation testing tool. The chamber is connected to a flow line for receiving fluid inside the chamber. A manual valve is placed inside the chamber while a hydraulically-operated valve is placed outside the chamber in the tank carrier for controlling the flow of the formation fluid into the chamber. The manual valve is set in the open position at the surface, while the hydraulically-operated valve is in the closed position. To collect a sample in the chamber, the pump is operated to withdraw the formation fluid and the hydraulically-operated valve is opened to allow the fluid to enter into the chamber. Upon retrieval of the chamber to the surface, the manual valve is closed to ensure no fluid leakage from the chamber, the hydraulically-operated valve disconnected and then the chamber is removed from the tank carrier. The manual valve is made of metal and includes a single seal point, which is prone to a common problem known as jetting which is caused by a combination of a high pressure differential across the seal and small flow areas across the seal. Jetting causes abrasive materials in the formation fluid to deteriorate the quality of the seal, which in turn may cause leakage. Any leakage from a sample chamber can negatively affect the quality of the collected sample. The manual valve's sensitivity to jetting makes it necessary to leave the valve open while down hole in addition to including the hydraulically-operated valve to control the flow of the formation fluid into the sample chamber.
The disclosure herein provides a formation evaluation system that utilizes a dual-seal valve that addresses some of the above-noted issues and may also be utilized inside a sample chamber, replacing the manual valve and eliminating the need of the hydraulically-operated valve.